棉酚对大鼠钾代谢的影响和某些可能协同因子(低钾、低镁摄入)的作用

棉酚是一种颇有希望的男子节育药。临床试用表明,其效果良好,然而可偶致低血钾性肌无力症,后者是否与棉酚有关,尚无定论。虽离体实验表明,棉酚可使心肌失钾;但在整体动物,一般均认为,棉酚不影响钾代谢。我们在常规、低钾及低镁饲养大鼠,观察了不同剂量棉酚对细胞内、外离子(主要是钾、镁)、可交换钾、某些肾功能及其它一些方面的影响,结果表明: 在低钾饲养大鼠,大剂量棉酚可引起骨骼肌胞内钾、镁离子浓度普遍下降;在常规饲养动物,同量棉酚只引起个别肌肉胞内钾离子浓度下降。据此,可以认为,棉酚可影响钾代谢,而低钾摄入可能为棉酚所致钾代谢障碍的一个协同因子。在低钾饲养大鼠,小剂量棉酚可使半数肌肉的胞内镁离子浓度下降;大剂量则使所有受测肌肉的胞内钾、镁离子浓度下降,但此时血清钾不降,尿浓缩功能保持良好。凡此均提示,棉酚所致钾代谢障碍可能与镁代谢紊乱有关。大剂量棉酚可引起骨骼肌的萎缩性改变,表现在体重和肌重下降,尿中肌酐系数下降以及以身长为尺度的可交换钾量减少。

THE INFLUENCE OF GOSSYPOL ON THE POTASSIUM METABOLISM OF RATS AND THE EFFECT OF SOME POSSIBLE CONTRIBUTING FACTORS (LOW-K AND LOW-MG INTAKE)

Gossypol was shown to be a male antifertility agent with a fairly good prospect. Clinical trials indicated that the antifertility effect of gossypol was excellent, but occasional cases of hypokalemic paralysis might occur in the course of its administration. As to the part played by gossypoi in the development of such hypokalemia there are contradictory opinions. In isolated heart it has been noticed that gossypol Could deplete myocardial K, but in intact animals most authors believe that gossypol may have no effect on K metabolism.In the present work the effect of gossypol on the concentrations of some of the extracellular and intracellular ions, the level of exchangeable potassium, certain renal functions, and some other aspects of the K metabolism are observed in rats fed regular diet, low-K diet, and low-Mg diet. Results indicate:1. In low-K fed animals large dose of gossypol decreases the intracellular K and Mg ion concentrations in all the four skeletal muscles in consideration, while in regularly fed animals it only decreases the intracellular K ion concentration of a single muscle. It may thus be concluded that in rats gossypol may affect K metabolism, and that low-K intake may be a contributing factor in the gossypol-induced disturbance of K metabolism.2. In low-K fed animals small dose of gossypol decreases the intracellular Mg ion concentration in two of the skeletal muscles; although large dose of gossypol decreases the intracellular K and Mg ion concentrations in all the muscles, it does not alter the serum K ion concentration, and at the same time the renal concentrating, ability remains unimpaired. These facts suggest that the gossypol-indueed disturbance of K metabolism might be the result of a perturbed Mg metabolism.3. Large dose of gossypol may bring about atrophic changes of the skeletal muscles, as evidenced by a decrease of the body weight and the weight of the muscles, a lowering of the urinary creatinine coefficient, and a decrease of the level of exchangeable potassium per unit length of the. body.